On one side are people like him, who dismiss the overwhelming medical consensus that the vaccines are effective and safe. These chiropractors closely follow the ideas espoused more than a century ago by the profession’s founder, Daniel David Palmer, who rejected germ theory and believed that diseases were caused by spinal misalignments called subluxations that disrupted an innate life force.

The chiropractic profession, which involves adjustment of the spine through manual manipulation and is sometimes just called chiropractic, “emerged from this vitalistic, almost supernatural idea of healing,” said Timothy Caulfield, the Canada research chair in health law and policy at the University of Alberta. “It’s difficult for them to escape their roots, and I think that’s one of the reasons that so many people continue to be attracted to chiropractic who are more likely to be vaccination hesitant, and why so many chiropractic practitioners are in fact vaccination hesitant.”...

Professor Caulfield’s research has found that people who are attracted to alternative therapies like chiropractic are “also the people who are likely to be susceptible to misinformation,” he said. “If you’re open to alternative medicine, you’re also more likely to be attracted to anti-vaccination rhetoric, so the ideas cluster.”